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How to measure heel length

I thought I understood and had my heel length down but the other day everything went to crap after I shaped / sharpened several 90/ 120 degree tools (tips breaking off on long heels / tip either diving into metal with short heel or skidding across brass; probably b/c tip snapped and i didn't see till it got worse). I think that my heel length is shorter than what I was using before and thought maybe I should measure the heel length to get positive results every time I engrave. I remember Sam saying the heel length needs to be less than 1/4 mm but do I measure from the tip straight back? And if a mm is 0.039" or 39 thousandth's on my dial calipers, then measuring this way my 120 tool is around 0.032" and it cuts well. My 90 dgree tool is around 0.010" and dives into the metal. I just wanted to understand this better before changing all my heels. Thanks in advace for any help.:thumbs up:

I think your problem is more to do with tool control than heel length.

Around 0.25mm is correct as a point of referenece. .........and maybe longer for straighter lines.

If you looked at 10 gravers from different engravers you will find quite a variation from no heel to quite long and everything in between. When sharpening you just look at it and think "that's about right"

Tips breaking can be caused by several things. Vibration in the work is a big one, holding the graver to the cut incorrectly or there may be a week spot in the graver itself etc etc. Or, if they are carbide you may be using too coarser grit and need to polish the heel.

Your angle of attack (when you first dive the graver into the metal) and what depth you level the graver out will determine the actual cut. If you try to cut deeper than the heel length then you will also strike problems.

If you are finding that the graver is diving into the work.......then you can do several things. The first is button back on the power you are giving the tool and the second is develop a lighter touch .........and the third is make the heel slightly longer. The first two will be more significant than the last.

There is no hard and fast formulas on any of this stuff. It's what works for you, and what dosn't. This will all come with time and practice and you will develop a "feel" for it. If you feel better using a longer heel then go with it.

However longer heels can bring on their own problems when doing fine work. Things like heel strike and burring the edge of tight turns. But there are ways around that as well.

Hello Andrew, thanks for responding once again to my questions.
I've been experimenting with diferrent heel lengths the last few hours and found one slighly less than 1/32 of an inch works well. Jerry Harper said the same thing about fine work as you did and said i'd want it half as long as normal. Now that I know how to measure the heel and have the confidence that it's the correct length, i'll be able to eyeball it next time. I was measuring from the tip along the side all this time, it was a wonder I was cutting anything, .
I really appreciate the info, us new engravers learn something everytime an experienced engraver types or speaks.:thumbs up:

All of what Andrew said but...
Are you just trying to cut some new brass of have you been doing it? It might be the material. Some brass can be real picky. Add to that if it isn't backed up proper it will be worse. Try a different material as well.
The more you engrave, the shorter you can make a heel.

Michael,
Hey , yeah, like Andrew says, I think you have to have a "feel" for what is going on with the graver. I cut h & c and I'm very much in tune with the sound, feel, pace / progression of the tool. I don't & never have measured any heel length, I just eyeball it with a loupe. It works for me. On any "important" piece after sharpening I will run the tool on a piece of scrap to make sure it is tracking correctly and behaving the way I expect. I do use a bit longer heal for straight lines & shorter for scroll work. I dont measure face angle either I try to avoid xtra hard or tough work if I think I may not be able to execute the design. Ain't worth the hassle. And some brass can be filthy to work with, I like to practice on mild steel. All things being equal, the more familiar you are with your tools the better cutting will emerge.

Rex / Ksnyder, thanks for responding. I tried a mild steel plate from grs and had the same problem. Now that you mention it, there was a different feel that didn't seem right and when I would check my tool, I found it chipped (when I tried a heel that was too long). I'm glad this happened because I now understand my tool better. I just got lucky up to now with getting my heel right and used to the really short heel, until it was too short and I plunged into the metal. The problem was I went too short. When I shaped a new graver blank from Ngraver into the 90 / 120 tool I did as instructed and formed the heel with only a ceramic lap with diamond spray. I could hold that tool there all day and all I got was a teeny tiny polished heel that I could only see with a 10x loupe.
I ended up forming a new heel on a graver blank with the 1200 wheel by lightly kissing the graver to the wheel (less than a secoond), forming each heel and then polishing on the ceramic lap. works fine now.
I'm sure glad this happened on a cheap pawn shop knife rather than my own or someone else's gun. Thanks again for all the help!:thumbs up:

I never use a diamond wheel to put a heel on a point graver, (By that I mean a square graver of any geometry) just the ceramic lap.
Point breakage is a common distraction for all of us and it usually happens when the tool point gets bound up in the cut.
Basically, it comes down to this:
The tool really is designed to cut a straight line---that's why we rotate the work. It will tolerate some movement, but not much.
I agree with Andrew---tool control.
You're catching on.....keep going.

I think the thing to keep in mind Michael when you are sharpening............is what you want the end result to be.

Polished heels and faces will give you brighter cuts whereas non polished ones will give you duller cuts. Jewellery cuts you probably want brighter to get that bling look. Darker cuts for gun work so you don't get that bling look. Wider gravers with bigger heels, and parallel heels, will give you more "flare" in your cut if you so desire.

Steeper faces will give you more tool/tip strength than narrower gravers with lower angled faces. This is important to remember when cutting extremely hard or soft metals. A steeper angled face makes it harder to see the point of your tool and can produce a slightly rougher cut. A lower angled face makes the tool tip easier to see and can produce a cleaner cut. Longer heels can be an aid to cutting long straight lines.

With your main cuts, you can sometimes get away with blunt tools if using a power graver............but the tip has to be razor sharp for shading cuts.

And on and on it goes ................and it all boils down to personal preference and what you are trying to achieve and what you like. I sharpen the way Marty describes but Brian prefers his polished. So there is no right or wrong of it.

One of the biggest things about all this is confidence. The confidence to experiment, and the confidence to attack the work in a manner that you know will work for you.

I always do the parallel heel and they're usually just a bright hairline. I normally do them with the 1200 grit wheel but I don't use any power. I hold the graver on the wheel and use my hand to turn the wheel about 1/4 turn.

I had terrible trouble controlling my 120 at first - thing would dive and climb like the pony ride at Wal-Mart. That turned out to be partly a problem of having my (parallel) heel too long.

Part of it is just going to be taking a couple of plates and cutting a lot of lines, just getting the feel of things.